Changing viewpoints in neurology as illustrated by certain aspects of cerebrovascular disease.
The touchstone of success in the progress of clinical neurology during the latter half of the last century was the careful correlation of clinical observations with the known anatomic facts and, later, the pathologic and physiologic knowledge of the central nervous system. During the past twenty-five years the limitations of this classical approach have become apparent, as has the need for newer methods and the adoption of a dynamic and functional concept to complement the static and structural one hitherto so successful. In respect to cerebrovascular disease, there are significant facts not readily explained in the relatively simple terms of morbid anatomy, such as the finding that in many cases of recent brain infarction no evidence of occlusion of an appropriate artery could be demonstrated, while on the other hand complete occlusion of a cerebral artery can occur without any resultant softening in the area of distribution. The increase in knowledge of the cerebral circulation derived from angiographic studies, and the progress in recognition of the very variable clinical syndromes produced by occlusions of the internal carotid and basilar arteries underline this change from a static to a dynamic concept of disease, a change which has been responsible for the exploitation of the technical advances in the fields of cerebral surgery, neuroradiology and neurophysiology. Inevitably such an approach will likewise insure the success of neurochemical and related techniques which, more and more, are being used in neurological investigation and on which the future growth of neurology increasingly depends.